1. Field of the Invention
This invention relates to methods of treating waste products, primarily silvicultural waste such as stumps and limbs, and to products formed from the treated waste products.
2. Description of the Related Art
Many different disposal and treatment processes have been developed to deal with the large volumes of wastes of various kinds which are produced by humans, some of which processes produce usable products. For example, the patent of Hartmann et al. (U.S. Pat. No. 4,420,320) provides a method of producing soil conditioners from waste material, such as refuse and sludge. Briquettes of the material are subjected to intense rotting to reduce the water content, and then the briquettes are ground and screened. The smaller particles are used as a soil conditioner and the larger ones are treated by low temperature carbonization or combustion.
Composting methods are often used to treat wastes containing plant matter. Composting results in extreme heating of the material being composted, requires the presence of a significant amount of moisture, and results in a humus-like final product. For example, the composting process of Willisch (U.S. Pat. No. 4,146,382) comprises grinding waste material to bring it to a predetermined size, and then bedding the material in successive self-aerating stacks having a honeycomb tunnel ventilation system, which is actively aerated. The resultant material may be used for compost.
City wastes, which are high in paper content, may be treated by being ground into small pieces, screened, and placed in a digester in layers that are turned over periodically with plowshares and are watered and held to retain a high temperature for the decomposition to proceed (U.S. Pat. No. 4,050,917).
Silvicultural wastes and other arboreal wastes are produced when land is cleared for highways, agriculture, and construction of buildings and other structures. The arboreal wastes produced are generally placed in landfills, bulldozed into unused areas, or burned, and often are not of further use.
Local and state governments have enacted rules to control how and where persons may dispose of such waste materials. For example, the North Carolina Administrative Code currently provides that "demolition landfills", which are defined as landfills that are limited to receiving stumps, limbs, leaves, concrete, brick, wood, uncontaminated earth or other solid wastes as approved, must have the waste placed therein restricted to the smallest area feasible, and must meet other requirements.
The North Carolina Administrative Code further defines "yard wastes", as being limited to stumps, limbs, leaves, grass and untreated wood, and specifies treatment by composting of the wastes. In such facilities, the particle size of the larger trash items such as limbs, trees, and stumps is required by law to be reduced to promote composting. The compost must also be aerated, such as by turning, elevated temperatures must be maintained, and nitrogen bearing waste such as grass clippings must be incorporated to aid in the microbial composting process.
Thus, the primary ways of disposing of many wastes, including the various wood-containing or related wastes, either do not utilize large waste pieces, do not result in a usable product, and/or require substantial labor.
It is therefore an object of this invention to provide a method for disposing of wood-containing wastes.
It is a further object of this invention to provide a method for disposing of wood-containing wastes which is of low labor intensity and does not required the use of grinding before disposal nor the addition of fertilizers or other chemicals.
It is a further object of this invention to provide a method for disposing of wood-containing wastes which produces an end product which may be used as soil to grow plants.
Other objects and advantages will be more fully apparent from the following disclosure and appended claims.